1. Field of the Invention
The present invention relates to a compressor for a scroll fluid apparatus, etc., and more particularly to a compressor suitably used for compressing fluid such as air.
2. Description of the Related Art
In conventional compressors in which to compress fluid such as air, the following scroll compressor has been known. That is, by driving an orbiting scroll to orbit relative to a fixed scroll by means of a driving source such as an electric motor, fluid is compressed sequentially in a compressed chamber placed between both of the scrolls (refer to, for example, Japanese Patent Application Laid-open No. H10-325396).
The conventional scroll compressor of this kind is provided with a back-pressure chamber where either one of the scroll members, the fixed scroll or the orbiting scroll, is pressed against the other scroll member. The scroll compressor can adjustably control pressure within the back-pressure chamber according to pressure of compressed fluid exhausted from the compressed chamber, whereby tip clearance of lap portions for both the fixed scroll and the orbiting scroll can be properly secured.
Here, in the scroll compressor with conventional technologies discussed above, the compressor only has a special back-pressure chamber on a rear side of the fixed scroll or the orbiting scroll and only adjustably control pressure within the back-pressure chamber according to pressure of an exhaust fluid (compressed fluid). Accordingly, until the pressure of the exhaust fluid is increased at an initial starting stage of the compressor, the pressure of the back-pressure chamber can not be controlled, whereby behavior of the orbiting scroll may be unstable.
Further, since the conventional scroll compressor is configured as that the special back-pressure chamber is provided on the rear side of the fixed scroll or the orbiting scroll, it is necessary to secure an additional space for the back-pressure chamber within a casing of the scroll compressor. With this, the overall architecture of the scroll compressor becomes complicated and enlarged in size, whereby it makes difficult to achieve small-size and weight-saving.